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Ultrafast dynamics on the electron-attachment process

(8 January 2018)

Prof Jan Verlet, Dr Joshua Rogers and Cate Anstöter have recently published their novel research in the prestigious journal, Nature Chemistry. They studied the reaction of an electron with a neutral molecule to make an anion. While this may seem like something that should be completely understood by now, it actually is not. One of the main reasons for this is that the process occurs on a very short time scale and it is therefore difficult to study experimentally. Jan's group has developed a method to track the reaction in real-time and to study the reaction of a very low-energy electron with hexafluorobenzene.

The group showed that the electron capture process proceeds via a recently postulated electronic state of the anion (called a non-valence correlation-bound state, which the group has very recently identified spectroscopically). This state captures the electron initially and then transfers it into a valence state (a “normal” anion) within 30 femtoseconds. They also show that the process is fully coherent. The importance of the finding is that they have discovered a new mechanism of electron attachment at low energy.

Electron attachment is not only of fundamental importance, but is also a key reaction occurring for example in plasma chemistry, radiation chemistry, electron transfer and electrochemistry, etc. A very nice example of the relevance is that anions have been observed in the interstellar medium, but the mechanism of how they are formed is not known. Their discovered mechanism explains how large poly-cyclic aromatic hydrocarbon anions might form.